Extending from the mouth to the anus, the outer walls of the gut are composed of layers of muscle and tissue that undergo peristalsis, or waves of contraction, which push the food along its path. Individual sections of the gut have their own names, but are all part of the same digestive canal. From the mouth, the gut extends into the pharynx and the esophagus, which in turn convey food to the stomach. After being partially digested in the stomach, the food is passed on to the small and then large intestines, before excess waste exits the body.